Ultraviolet rays, depending on the dose, have a different effect on organisms. Excessive radiation can cause great harm to the body: damage chromosomes, cause premature aging, and cause cataracts. And irradiation in small doses has a positive effect on the growth and development of the human skeleton, the rays stimulate the synthesis of the skin pigment melanin and vitamin D.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.